breakpad/src/client/linux/log/log.h
primiano@chromium.org 6ea9219d80 [microdump] Move microdump writes to the crash ring-buffer log
So far the microdump_writer dumped the log in logcat using the default
system log. This is simple to achieve but has some drawbacks:
 1. Creates spam in the system log, pushing back other eventual useful
    messages.
 2. There is a high chance that the microdump gets lost if some log
    spam storm happens immediately after a crash and before the log
    is collected by the feedback client.
 3. Since Android L, the logger is smartly throttling messages (to
    reduce logcat spam). Throttling brekpad logs defeats the all
    point of microdumps.

This change is conceptually very simple. Replace the use of
__android_log_write() with __android_log_buf_write(), which takes
an extra bufID argument. The main drawback is that the
__android_log_buf_write is not exported in the NDK and needs to be
dynamically looked up via dlsym.
This choice has been discussed and advocated by Android owners.
See the internal bug b/21753476.

BUG=chromium:512755
R=thestig@chromium.org

Review URL: https://codereview.chromium.org/1286063003 .

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1490 4c0a9323-5329-0410-9bdc-e9ce6186880e
2015-08-17 10:32:26 +00:00

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// Copyright (c) 2012, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef CLIENT_LINUX_LOG_LOG_H_
#define CLIENT_LINUX_LOG_LOG_H_
#include <stddef.h>
namespace logger {
int write(const char* buf, size_t nbytes);
// In the case of Android the log can be written to the default system log
// (default behavior of write() above, or to the crash log (see
// writeToCrashLog() below).
#if defined(__ANDROID__)
// The logger must be initialized in a non-compromised context.
void initializeCrashLogWriter();
// Once initialized, writeToCrashLog is safe to use in a compromised context,
// even if the initialization failed, in which case this will silently fall
// back on write().
int writeToCrashLog(const char* buf);
#endif
} // namespace logger
#endif // CLIENT_LINUX_LOG_LOG_H_